Substrate processing apparatus and substrate processing method

ABSTRACT

An apparatus includes: a processing container; a stage provided inside the processing container to place a substrate thereon; a gas supply mechanism for supplying a processing gas into the processing container; and at least three ultraviolet light sources provided to irradiate the processing gas inside the processing container with ultraviolet rays. The ultraviolet light sources are provided to be offset from a rotation axis of the stage in a plan view, and are arranged in a light source arrangement direction with distances from the ultraviolet light sources to the rotation axis being different from one another. The ultraviolet light sources include first to third ultraviolet light source. The third ultraviolet light source is arranged such that distances L1, L2, and L3 from the first to third ultraviolet light sources, respectively, to the rotation axis in a plan view satisfies a relationship of L1&lt;L3&lt;L2.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2019-049162, filed on Mar. 15, 2019, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a substrate processing apparatus and asubstrate processing method.

BACKGROUND

Patent Document 1 discloses a substrate processing apparatus in which anoxide film is formed on a silicon substrate by performing an ultravioletradical oxidation process on the silicon substrate, and a radicalnitridation process is performed on the oxide film using high-frequencyremote plasma. Such a substrate processing apparatus includes aprocessing container in which an internal processing space is defined, aholding member that holds a substrate to be processed loaded into theprocessing space, a rotational driving part that rotates a shaft of theholding member, and two ultraviolet light sources that irradiate theprocessing space with ultraviolet rays.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-119522

SUMMARY

According to an embodiment of the present disclosure, there is provideda substrate processing apparatus for processing a substrate, including:a processing container in which the substrate is accommodated; a stageprovided inside the processing container, and configured to place thesubstrate thereon and rotate about a rotation axis thereof; a gas supplymechanism configured to supply a processing gas into the processingcontainer; and at least three ultraviolet light sources provided in anarea that faces a placement surface of the stage on which the substrateis placed, and configured to irradiate the processing gas inside theprocessing container with ultraviolet rays, wherein irradiationintensities of the ultraviolet rays irradiated from the at least threeultraviolet light sources are the same, wherein the at least threeultraviolet light sources are provided to be offset from the rotationaxis of the stage in a plan view, and are arranged in a light sourcearrangement direction that is a predetermined direction parallel to theplacement surface of the stage in a plan view with distances from the atleast three ultraviolet light sources to the rotation axis of the stagebeing different from one another, wherein the at least three ultravioletlight sources include a first ultraviolet light source disposed closestto the rotation axis of the stage in a plan view, a second ultravioletlight source disposed at an outermost position in a plan view andarranged near a peripheral edge of the stage, and a third ultravioletlight source other than the first and second ultraviolet light sources,and wherein the third ultraviolet light source is arranged such thatdistances L1, L2, and L3 from the first ultraviolet light source, thesecond ultraviolet light source, and the third ultraviolet light source,respectively, to the rotation axis of the stage in a plan view satisfiesa relationship of L1<L3<L2.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the presentdisclosure, and together with the general description given above andthe detailed description of the embodiments given below, serve toexplain the principles of the present disclosure.

FIG. 1 is a vertical cross-sectional view schematically illustrating anoutline of a configuration of a substrate processing apparatus accordingto a present embodiment.

FIG. 2 is a horizontal cross-sectional view schematically illustratingan outline of a configuration of the substrate processing apparatusaccording to the present embodiment.

FIG. 3 is a schematic explanatory view of a gas cooling mechanismprovided in the substrate processing apparatus.

FIG. 4 is a schematic explanatory view of a liquid cooling mechanismprovided in the substrate processing apparatus.

FIG. 5 is a graph illustrating in-plane distributions of ultravioletintensities on upper surfaces of substrates in Examples 1 to 3 andComparative Examples 1 to 3.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments, examples ofwhich are illustrated in the accompanying drawings. In the followingdetailed description, numerous specific details are set forth in orderto provide a thorough understanding of the present disclosure. However,it will be apparent to one of ordinary skill in the art that the presentdisclosure may be practiced without these specific details. In otherinstances, well-known methods, procedures, systems, and components havenot been described in detail so as not to unnecessarily obscure aspectsof the various embodiments.

As an oxide film producing apparatus for generating an oxide film on asemiconductor wafer (hereinafter, referred to as a “wafer”), there isknown an apparatus that irradiates ultraviolet rays to the interior of aprocessing container while supplying a processing gas containing anoxygen gas into the processing container in which a processing space forprocessing a wafer is formed (see e.g., Patent Document 1). Theultraviolet rays are absorbed by the oxygen gas in the processing gas sothat oxygen radicals are generated on a front surface of the wafer. Thefront surface of the wafer is oxidized by the oxygen radicals to form anoxide film. Further, the substrate processing apparatus disclosed inPatent Document 1 has two ultraviolet light sources that irradiateultraviolet light to the processing space in the processing container.

In addition, the above-described oxide film producing apparatus isprovided with a rotational driving mechanism that rotates a holder forholding the wafer such that uniform film formation is performed on thefront surface of the wafer.

In the oxide film producing apparatus provided with the two ultravioletlight sources and the rotational driving mechanism as described above,one of the two ultraviolet light sources is provided at a positionslightly offset from the center of the holder, namely the center of thewafer in a plan view, and the other one is disposed at a positioncorresponding to peripheral edge of the holder, namely at a peripheraledge of the wafer. This is for making the film quality, such as thethickness of an oxide film to be formed, uniform in the plane of thewafer by making the irradiation amount of ultraviolet rays uniform inthe plane of the wafer.

In the case where the two ultraviolet light sources are provided at thepositions described above, in order to make the film quality of theoxide film more uniform in the plane of the wafer, it is necessary tosuppress output of ultraviolet rays from the ultraviolet light sourceprovided near the center of the wafer, compared with the ultravioletlight source provided near the peripheral edge of the wafer. Forexample, it is necessary to set the output of the ultraviolet lightsource provided near the center of the wafer to 40% of the maximumoutput of the respective light source while setting the output of theultraviolet light source provided near the peripheral edge of the waferto 80% of the maximum output of the respective light source.

When forming an oxide film, it is also required to increase a formationrate of the oxide film, namely to improve a film formation throughput.As a method of increasing the formation rate of the oxide film, a methodof increasing the output of an ultraviolet light source may beconsidered. However, in the case where two ultraviolet light sources areprovided as described above, when the output of not only the ultravioletlight source provided near the center of the wafer but also theultraviolet light source provided near the peripheral edge of the waferis increased to approach the maximum outputs of the respective lightsources, the in-plane uniformity of film quality of the wafer may beimpaired.

Therefore, the technology according to the present disclosure increasesthe formation rate of an oxide film while maintaining the in-planeuniformity of film quality.

Hereinafter, the configuration of a substrate processing apparatusaccording to the present embodiment will be described with reference tothe drawings. In the specification, elements having substantially thesame functional configurations will be denoted by the same referencenumerals, and redundant explanations thereof will be omitted.

FIGS. 1 and 2 are vertical and horizontal cross-sectional views,respectively, schematically illustrating an outline of a configurationof a substrate processing apparatus according to the present embodiment.The substrate processing apparatus of the present embodiment forms asilicon oxide film on a front surface of a silicon substrate W having adiameter of 300 mm by ultraviolet radical oxidation process, and thenperforms remote plasma radical nitridation process so as to nitride afront surface of the silicon oxide film.

As illustrated in FIG. 1, the substrate processing apparatus 1 includesa processing container 10 configured to be capable of beingdepressurized and to accommodate therein a silicon substrate W (whichmay be referred to as a “substrate W” below).

The processing container 10 has a processing space S therein, and isconfigured in a rectangular parallelepiped shape using, for example, ametal material.

A loading/unloading port 11 through which the substrate W is transferredis provided in a sidewall 10 a of the processing container 10. A gatevalve 12 configured to open/close the loading/unloading port 11 isprovided in the loading/unloading port 11.

A stage 13 as a placement part is provided inside the processingcontainer 10. The stage 13 is formed, for example, in a circular shapein a plan view and the substrate W is horizontally placed on an uppersurface 13 a of the stage 13. Hereinafter, the upper surface 13 a of thestage 13 is sometimes referred to as a “placement surface 13 a”. Thestage 13 is provided with a heater (not illustrated) for heating thesubstrate W. In addition, the stage 13 is configured to be rotatable bybeing driven by a rotational driving part (not shown) with the centeraxis thereof as a rotation axis 13 b.

A gas introduction part 14 is provided inside the processing container10 so as to introduce an oxygen gas as a processing gas into theprocessing container 10. The gas introduction part 14 is disposed, forexample, at a position outside the stage 13 and facing theloading/unloading port 11 in a plan view. As illustrated in FIG. 2, aplurality of injection ports 14 a are formed in the gas introductionpart 14 so as to be arranged in a width direction (Y-axis direction inFIG. 2). A gas supply mechanism 20 is connected to the gas introductionpart 14 such that the oxygen gas can be injected into the processingspace S from the injection ports 14 a Specifically, one end of a supplypipe 22 is connected to a source 21 for storing the oxygen gas in thegas supply mechanism 20 and the other end thereof is connected the gasintroduction part 14.

In addition, an exhaust hole 15 is formed in a bottom wall 10 b of theprocessing container 10. The exhaust hole 15 is disposed, for example,at a position outside the stage 13 and facing the gas introduction part14 in a plan view. An upper end of the exhaust hole 15 is exposed to theprocessing space S. An exhaust mechanism 30 is connected to the exhausthole 15 such that the processing space S can be exhausted from theexhaust hole 15. Specifically, one end of an exhaust pipe 32 isconnected to an exhaust device 31 including a vacuum pump and the likein the exhaust mechanism 30, and the other end there of is connected tothe exhaust hole 15. Further, the exhaust hole 15 is formed to extend ina width direction (the Y-axis direction in FIG. 2).

Since the stage 13, the gas introduction part 14, and the exhaust hole15 are in the above-described positional relationship, the oxygen gasintroduced from the gas introduction part 14 passes over the stage 13and flows toward the exhaust hole 15. In the following description, theupstream side in the flow direction of the oxygen gas is sometimesreferred to as a “front side,” and the downstream side thereof issometimes referred to as a “back side.”

A supply hole 16 is formed in the sidewall 10 a of the processingcontainer 10 at the front side. A remote plasma supply mechanism 40 isconnected to the supply hole 16 such that nitrogen radicals can besupplied into the processing space S through the supply hole 16.Specifically, one end of supply pipe 42 is connected to a remote plasmasource 41 of the remote plasma supply mechanism 40 and the other endthereof is connected to the supply hole 16. The remote plasma source 41can activate by plasma an inert gas such as an argon gas or the like anda nitrogen-containing gas such as a nitrogen gas (N₂ gas) or the likesupplied to the remote plasma source 41 so as to form nitrogen radicals.

An ultraviolet irradiation mechanism 50 including an ultraviolet lightsource 51 is installed on an upper portion on the outside of theprocessing container 10 such that the ultraviolet light source 51 forirradiating ultraviolet rays into the processing container 10 is locatedin an area facing the placement surface 13 a of the stage 13. Theultraviolet irradiation mechanism 50 irradiates the processing container10 with the ultraviolet rays from the ultraviolet light source 51through openings 17 formed in a ceiling wall 10 c of the processingcontainer 10. The ultraviolet light source 51 is formed in a linearshape, and irradiates the processing space S of the processing container10 with ultraviolet rays having a wavelength of 172 nm through opticalwindows 18 provided in the openings 17 in the ceiling wall 10 c of theprocessing container 10. As a material of the optical window 18, amaterial that transmits the ultraviolet rays, for example, quartz, maybe used.

Further, three ultraviolet light sources 51 are provided. Each of theultraviolet light sources 51 is arranged to extend in a width direction(the Y-axis direction in FIG. 2). In the present embodiment, the opticalwindows 18 are individually provided for the three ultraviolet lightsources 51, respectively.

Distances from the three ultraviolet light sources 51 to the substrate Won the stage 13 (specifically, distances from the centers of the threeultraviolet light sources 51 to an upper surface of the substrate W) arethe same as one another. For example, the distance may be 120 mm to 150mm. Further, a distance from each of the optical windows 18 to thesubstrate W on the stage 13 (specifically, a distance from a lowersurface of each optical window 18 to the upper surface of the substrateW) is, for example, 70 mm to 120 mm.

The three ultraviolet light sources 51 are the same kind of lightsources, and have the same maximum output and the same length (in theY-axis direction in FIG. 2). In addition, the three ultraviolet lightsources 51 are controlled such that the outputs from the ultravioletlight sources 51 are equal to one another when the oxide film is formed.

The three ultraviolet light sources 51 are arranged in a light sourcearrangement direction (the X-axis direction in FIG. 2, namely thefront-back direction), which is a predetermined direction parallel tothe placement surface 13 a of the stage 13 in a plan view. In thepresent embodiment, the light source arrangement direction and the flowdirection of the oxygen gas coincide with each other, and the extensiondirection of the ultraviolet light sources 51 and the flow direction ofthe oxygen gas are orthogonal to each other.

In addition, in a plan view, none of the three ultraviolet light sources51 is located on the rotation axis 13 b of the stage 13, namely thecenter of the substrate W placed on the stage 13. That is, the threeultraviolet light sources 51 are located to be offset from the rotationaxis 13 b, namely the center of the substrate W.

Further, in a plan view, the distances from the three ultraviolet lightsources 51 to the rotation axis 13 b of the stage 13, namely the centerof the substrate W placed on the stage 13 (which is sometimes referredto as “the center of the substrate W” below), are different from oneanother. Details thereof are as follows.

Here, among the three ultraviolet light sources 51, the one disposed ata position closest to the center of the substrate W in a plan view willbe referred to as a first ultraviolet light source 51 i. In addition,the one disposed farthest from the center of the substrate W in a planview at an area corresponding to the peripheral edge of the substrate Wwill be referred to as a second ultraviolet light source 51 ₂.Specifically, the second ultraviolet light source 51 ₂ is disposed suchthat the center thereof is located in an area outside the peripheraledge of the substrate W. And among the three ultraviolet light sources51, the remaining one, other than the above ultraviolet light sources,will be referred to as a third ultraviolet light source 51 ₃. At thistime, assuming that the distances from the first to third ultravioletlight sources 51 ₁, to 51 ₃ to the center of the substrate W in a planview are L1 to L3, respectively, the third ultraviolet light source 51 ₃is disposed to have a relationship of L1<L3<L2.

More specifically, the first ultraviolet light source 51 ₁ is disposedsuch that the distance L1 to the center of the substrate W (hereinafter,also referred to as an “offset amount L1”) is 25 mm to 50 mm, the secondultraviolet light source 51 ₂ is disposed such that the distance L2 tothe center of the substrate W (hereinafter, also referred to as an“offset amount L2”) is 160 mm to 190 mm, and the third ultraviolet lightsource 51 ₃ is disposed such that the distance L3 to the center of thesubstrate W (hereinafter, also referred to as an “offset amount L3”) is90 mm to 120 mm.

More specifically, the first to third ultraviolet light sources 51 ₁ to51 ₃ are arranged at regular intervals in the light source arrangementdirection (the X-axis direction in FIG. 2).

In other words, the first to third ultraviolet light sources 51 ₁ to 51₃ are arranged so as to satisfy Equation (1) below.

L3+L1=L2−L1  (1)

For example, the first ultraviolet light source 51 ₁ is disposed to havethe offset amount L1 of 35 mm, the second ultraviolet light source 51 ₂is disposed to have the offset amount L2 of 175 mm, and the thirdultraviolet light source 51 ₃ is disposed to have the offset amount L3of 105 mm.

In the present embodiment, when the origin (reference point) in thelight source arrangement direction (the X-axis direction in FIG. 2,namely the front-back direction: the upstream side in the flow directionof the oxygen gas being referred to as the front side, and thedownstream side being referred to as the back side) is defined as therotation axis of 13 b of the stage 13, namely the center of thesubstrate W placed on the stage, the first ultraviolet light source 51 ₁and the second ultraviolet light source 51 ₂ are located on the positiveside in the light source arrangement direction (the positive side in theX-axis direction in FIG. 2, namely the front side). The thirdultraviolet light source 51 ₃ is located on the negative side in thelight source arrangement direction (the negative side in the X-axisdirection in FIG. 2, namely the back side).

Next, wafer processing performed using the substrate processingapparatus 1 will be described.

First, the gate valve 12 is opened, and a transfer mechanism (notillustrated), which holds the substrate W, is inserted into theprocessing container 10 via the loading/unloading port 11. Then, thesubstrate W is delivered between the transfer mechanism and the stage 13via support pins (not illustrated). Thereafter, the transfer mechanismis withdrawn from the processing container 10, and the gate valve 12 isclosed. Subsequently, the oxygen gas is supplied from the gas supplymechanism 20 into the processing space S of the processing container 10through the gas introduction part 14, and the processing space S isexhausted by the exhaust mechanism 30. During the formation of the oxidefilm, an oxygen gas of 100 sccm to 1,500 sccm is introduced, and theinterior of the processing container 10 is adjusted to a predeterminedpressure set in a range of 0.1 Torr to 10 Torr. During the formation ofthe oxide film, the temperature of the substrate W is adjusted to apredetermined temperature set in a range of 500 degrees C. to 1.000degrees C. by the heater (not illustrated) provided in the stage 13.During the formation of the oxide film, the stage 13 on which thesubstrate W is placed is rotated about the rotation axis 13 b by therotational driving part (not illustrated).

Thereafter, the three ultraviolet light sources 51 are driven for apredetermined period of time, and the processing space S irradiated withultraviolet rays through the optical windows 18. The ultraviolet raysare absorbed by oxygen in the oxygen gas in the processing space S, andoxygen radicals are formed. The oxygen radicals oxidize the frontsurface of the substrate W. By irradiating the ultraviolet rays for thepredetermined period of time, a silicon oxide film having a thickness of0.2 nm to 2 nm is formed on the front surface of the substrate W.

Next, the driving of the ultraviolet light sources 51 and theintroduction of the oxygen gas into the processing space S are stopped,and the oxygen gas inside the processing container 10 is discharged.Subsequently, nitrogen radicals generated by the remote plasma source 41are supplied to the processing space S for a predetermined period oftime. The nitrogen radicals in the remote plasma source 41 are generatedby supplying an argon gas and a nitrogen gas and plasma-exciting them byhigh-frequency waves. During the nitridation process, a nitrogen gas of1 sccm to 1.000 sccm and an argon gas of 100 sccm to 2,000 sccm aresupplied to the remote plasma source 41, an internal pressure of theprocessing container 10 is adjusted to 0.01 to 50 Torr, and atemperature of the substrate W is adjusted to 500 degrees C. to 1,000degrees C. Even during the nitridation process, the stage 13 on whichthe substrate W is placed is also rotated about the rotation axis 13 bby the rotational driving part (not illustrated).

After the nitridation process, the substrate W is unloaded from theprocessing container 10 in the order opposite to the order of loadingthe substrate W.

As described above, in the present embodiment, three ultraviolet lightsources 51 are provided, and each of these three ultraviolet lightsources 51 is offset from the rotation axis 13 b of the stage 13, namelyfrom the center of the substrate W, in a plan view. In addition, thethree ultraviolet light sources 51 are arranged along the light sourcearrangement direction in a plan view, and have different distances tothe center of the substrate W. In addition, the first to thirdultraviolet light sources 51 ₁ to 51 ₃ included in the three ultravioletlight sources 51 are arranged such that the offset amounts L1 to L3 havethe positional relationship of L1<L3<L2. Therefore, the followingeffects are obtained.

That is, unlike the present embodiment, in a case where only the firstultraviolet light source 51 ₁ and the second ultraviolet light source 51₂ are provided and the outputs of the ultraviolet rays from therespective ultraviolet light sources 51 are equal, the irradiationamount becomes smaller in a portion closer to the outside of the stage13 in a plan view, namely a portion closer to the outside of thesubstrate W. In the present embodiment, from the third ultraviolet lightsource 51 ₃ having the same ultraviolet output as the first ultravioletlight source 51 ₁ and the second ultraviolet light source 51 ₂ andhaving the above-described positional relationship with the firstultraviolet light source 51 ₁ and the second ultraviolet light source 51₂, ultraviolet rays are irradiated to the above-mentioned portion wherethe irradiation amount is small. Accordingly, by the ultravioletirradiation using the first to third ultraviolet light sources 51 ₁ to51 ₃ having the same ultraviolet output, it is possible to make theirradiation amount of ultraviolet rays uniform in the plane of thesubstrate W in a plan view.

Since the ultraviolet outputs of the first to third ultraviolet lightsources 51 ₁ to 51 ₃ are equal to one another, the output of each of thefirst to third ultraviolet light sources 51 ₁ to 51 ₃ including theoutput of the first ultraviolet light source 51 ₁ provided near thecenter of the substrate W may be increased to the maximum output of thelight source 51.

Accordingly, according to the present embodiment, it is possible toincrease the formation rate of the silicon oxide film while maintainingthe in-plane uniformity of the film quality, such as the film thickness.

In addition, in the present embodiment, the first ultraviolet lightsource 51 ₁ and the second ultraviolet light source 51 ₂ are located onthe positive side in the light source arrangement direction, and thethird ultraviolet light source 51 ₃ is located on the negative side inthe light source arrangement direction. Accordingly, even when each ofthe first to third ultraviolet light source 51 ₁, 51 ₂, and 51 ₃ isthick, the first to third ultraviolet light sources 51 ₁ to 51 ₃ can bearranged such that the offset amounts L1 to L3 satisfy the positionalrelationship of L<L3<L2.

In addition, in the above embodiment, the number of third ultravioletlight sources 51 ₃ is one, but a plurality of third ultraviolet lightsources may be provided.

As described above, the substrate processing apparatus 1 includes theoptical windows 18 and the ultraviolet light sources 51. The opticalwindows 18 may be heated to a high temperature by radiant heat from theheater (not illustrated) provided for the stage 13. At such a hightemperature, the light transmittances of the optical windows 18 maydecrease. Further, the ultraviolet light sources 51 may be heated to ahigh temperature due to their intrinsic heat generation or the like.Thus, when used at such a high temperature, the lifespan of theultraviolet light sources 51 may be shortened. Therefore, the substrateprocessing apparatus 1 has a mechanism configured to cool down theoptical windows 18 and the ultraviolet light sources 51 as describedbelow.

FIG. 3 is a schematic explanatory view of a gas cooling mechanism 60included in the substrate processing apparatus 1, in which the vicinityof the optical window 18 on the ceiling wall 10 c of the processingcontainer 10 is illustrated and the ceiling wall 10 c is illustrated incross section. As illustrated in FIG. 3, the gas cooling mechanism 60 isa mechanism configured to cool the optical windows 18 and theultraviolet light sources 51 with a nitrogen gas as a cooling gas, andincludes jet ports 61 and an annular path 62 formed in the ceiling wall10 c of the processing container 10.

Each jet port 61 is formed such that one end thereof is exposed at theopening 17 of the ceiling wall 10 c, below which the optical window 18is provided, and such that the nitrogen gas jetted therefrom is directedtoward the optical window 18, namely downward. In the example shown inFIG. 3, a set of jet ports 61 facing each other are formed with theopening 17 interposed therebetween. A plurality of sets of jet ports 61may be provided.

The annular path 62 is formed to be connected to the other ends of thejet ports 61 and surround the opening 17. The annular path 62 isconnected to the other end of a nitrogen gas supply pipe (notillustrated). One end of the nitrogen gas supply pipe is connected to anitrogen gas source (not illustrated).

With the above configuration, it is possible to inject the nitrogen gasfrom the nitrogen gas source to the optical window 18 through thenitrogen gas supply pipe, the annular path 62, and the jet ports 61.This allows cooling of the optical window 18 and thus prevents adecrease in the transmittance of the optical window 18. In addition,since the ultraviolet light source 51 disposed at a position facing theoptical window 18 can also be cooled down by the nitrogen gas injectedto the optical window 18, it is possible to prolong the lifespan of theultraviolet light source.

Further, it is possible to discharge ozone, generated outside theprocessing container 10 by the ultraviolet rays from the ultravioletlight source 51, by the nitrogen gas injected to the optical window 18.In other words, the cooling nitrogen gas injected to the optical window18 may also serve as a purge gas for discharging the ozone. In addition,the ozone is discharged through a discharge port (not illustrated)provided in a cover 52 (see FIG. 1) that covers the three ultravioletlight sources 51.

The cooling gas is not limited to the nitrogen gas, but may be, forexample, another inert gas.

FIG. 4 is a schematic explanatory view of a liquid cooling mechanism 70provided in the substrate processing apparatus 1, in which a partiallyenlarged upper surface of the ceiling wall 10 c of the processingcontainer 10 is illustrated.

As described above, the optical windows 18 are provided individuallycorresponding to the three ultraviolet light sources 51 ₁, 51 ₂, and 51₃. In other words, three optical windows 18 are provided.

The liquid cooling mechanism 70 has a single liquid flow path 71 throughwhich water serving as a cooling liquid flows. All of the three opticalwindows 18 are cooled down by the single liquid flow path 71. The singleliquid flow path 71 connects a single supply port 72 and a singledischarge port 73, and is formed so as to cover at least three sides ofeach of the rectangular optical windows 18 in a plan view. Morespecifically, the single liquid flow path 71 has a shape formed in aunicursal manner.

Since the liquid cooling mechanism 70 has the single supply port 72 andthe single discharge port 73, it is easy to attach/detach a water supplypipe. That is, according to the present embodiment, by using a structurethat is easy to attach and detach the water supply pipe, it is possibleto prevent transmittances of all optical windows from being reduced.

In addition, the cooling liquid used in the liquid cooling mechanism 70is not limited to water, and may be another liquid.

In the above example, the formation of the silicon oxide film and thenitridation process of the silicon oxide film are continuously performedinside the same processing container 10. However, the technologyaccording to the present disclosure may also be applied to forming othersilicon oxide films. In addition, the technology according to thepresent disclosure may be applied to forming an oxide film other than asilicon oxide film.

In the above description, the oxygen (O₂) gas is used as the processinggas for oxidation, but another oxygen-containing gas may be used.

In the above description, the gas introduction part 14 is providedoutside the stage 13 in a plan view, and the oxygen gas as theprocessing gas is supplied from a lateral side of the substrate W so asto flow along the front surface of the substrate W. However, thetechnology according to the present disclosure may also be applied tosupplying the processing gas from above so as to collide with the frontsurface of the substrate. That is, the technology according to thepresent disclosure may be applied to supplying the processing gas notonly in a side-flow manner but also in a down-flow manner.

It should be noted that the embodiments disclosed herein are exemplaryin all respects and are not restrictive. The above-described embodimentsmay be omitted, replaced or modified in various forms without departingfrom the scope and spirit of the appended claims.

Examples

In Examples 1 to 3, ultraviolet irradiation was performed in asimulation using the substrate processing apparatus 1 according to thepresent embodiment. The offset amounts L1 to L3 of the ultraviolet lightsources 51 ₁, 51 ₂, and 51 ₃ in Examples 1 to 3 were as follows, and theoutput of each of the ultraviolet light sources 51 ₁, 51 ₂, and 51 ₃ wasset to 80% of the maximum output thereof.

-   -   Example 1: L1=35 mm, L2=175 mm, and L3=105 mm    -   Example 2: L1=45 mm, L2=175 mm, and L3=110 mm    -   Example 3: L1=28.5 mm, L2=174.5 mm, and L3=101.5 mm

In Comparative Example 1, ultraviolet irradiation was performed in asimulation using a substrate processing apparatus, which has the firstto third ultraviolet light sources 51 ₁ to 51 ₃, similar to thesubstrate processing apparatus 1 according to the present embodiment,but in which the first ultraviolet light source 51 ₁ is not provided tobe offset. In Comparative Example 1, the offset amounts L1 to L3 of theultraviolet light sources 51 ₁, 51 ₂, and 51 ₃ were as follows, and theoutput of each of the ultraviolet light sources 51 ₁, 51 ₂, and 51 ₃ wasset to 80% of the maximum output thereof.

-   -   Comparative Example 1: L1=0 mm, L2=130 mm, and L3=175 mm

In Comparative Example 2, ultraviolet irradiation was performed in asimulation using a substrate processing apparatus, which has the firstto third ultraviolet light sources 51 ₁ to 51 ₃, similar to thesubstrate processing apparatus 1 according to the present embodiment,but in which the offset amount L3 of the third ultraviolet light source51 ₃ is equal to the offset amount L2 of the second ultraviolet lightsource 51 ₂. In Comparative Example 2, the offset amounts L to L3 of theultraviolet light sources 51 ₁, 51 ₂, and 51 ₃ were as follows, and theoutput of each of the ultraviolet light sources 51 ₁, 51 ₂, and 51 ₃ wasset to 80% of the maximum output thereof.

-   -   Comparative Example 2: L1=45 mm, L2=175 mm, and L3=175 mm

In Comparative Example 3, ultraviolet irradiation was performed in asimulation using a substrate processing apparatus, which has only thefirst ultraviolet light source 51 ₁ and the second ultraviolet lightsource 51 ₂, unlike the substrate processing apparatus 1 according tothe present embodiment. In Comparative Example 3, the offset amounts L1and L2 of the ultraviolet light sources 51 ₁ and 51 ₂ and the output ofeach of the ultraviolet light sources 51 and 51 ₂ are as follows.

-   -   Comparative Example 3: L1=45 mm and L2=175 mm    -   Output of the first ultraviolet light source 51 ₁=40% of the        maximum output    -   Output of the second ultraviolet light source 51 ₂=80% of the        maximum output

In Examples 1 to 3 and Comparative Examples 1 to 3, the distance fromeach of the ultraviolet light sources 51 ₁, 51 ₂, and 51 ₃ to the uppersurface of the substrate W was 136 mm, and the distance from the uppersurface of the substrate W to the lower surface of each optical window18 was 93 mm.

FIG. 5 is a graph illustrating in-plane distributions of ultravioletintensities on the upper surfaces of substrates W in Examples 1 to 3 andComparative Examples 1 to 3. In FIG. 5, the horizontal axis representsthe distances of areas on the substrates W from the centers of thesubstrates W. and the vertical axis represents the ultravioletintensities in areas on the substrates W.

As illustrated in FIG. 5, in Comparative Example 1, although theultraviolet intensity on the upper surface of the substrate W was higherthan that in Comparative Example 3, the in-plane variation was large.Specifically, assuming that an in-plane variation Δ of the ultravioletintensity is defined as a ratio of a difference between the maximumvalue I_(max) and the minimum value I_(min) of the ultraviolet intensitywith respect to the average value I_(ave) of the ultraviolet intensity(Δ=100×(I_(max)−I_(min))/I_(ave)), the in-plane variation Δ inComparative Example 1 exceeded 23%. In addition, in Comparative Example2, although the in-plane variation Δ of the ultraviolet intensity wassmaller than that in Comparative Example 1, the ultraviolet intensity onthe upper surface of the substrate W was smaller than that inComparative Example 1.

In contrast, in Examples 1 to 3, the ultraviolet intensity on the uppersurface of each substrate W was higher than those in ComparativeExamples 2 and 3, and was almost the same as in Comparative Example 1.In addition, in Examples 1 to 3, the in-plane variation Δ of theultraviolet light intensity was smaller than those in ComparativeExamples 1 and 2, and was almost the same as in Comparative Example 3.Specifically, the in-plane variation Δ of the ultraviolet intensity was13.7% in Comparative Example 2 and 14.5% in Comparative Example 3, butwas 6.9% in Example 1, 10.0% in Example 2, and 11.3% in Example 3.

In addition, a process of forming a silicon oxide film was actuallyperformed under the same conditions as in Example 1 and ComparativeExample 3 and by setting, at the time of ultraviolet irradiation, theinternal pressure of the processing container 10 to 0.5 Torr, the flowrate of the oxygen gas to 450 sccm, the irradiation time to 120 seconds,and the temperature of the substrate W to 800 degrees C. In this case,under the same conditions as in Comparative Example 3, in which thenumber of the ultraviolet light sources 51 is two, the average thicknesswas 1.11 nm and a 1σ% value indicating the in-plane variation (a valueobtained by dividing the standard deviation σ by the average value andexpressed in percentage) was 0.80%. In contrast, under the sameconditions as in Example 1, the average thickness was 1.26 nm and the1σ% value was 0.85%. That is, according to Example 1, it is possible toincrease the formation rate of the oxide film to be higher than that inComparative Example 3 while suppressing the in-plane variation of thefilm thickness to be equal to that in Comparative Example 3.

The following configurations also belong to the technical scope of thepresent disclosure.

(1) A substrate processing apparatus for processing a substrate,includes: a processing container in which the substrate is accommodated;a stage provided inside the processing container, and configured toplace the substrate thereon and rotate about a rotation axis thereof; agas supply mechanism configured to supply a processing gas into theprocessing container; and at least three ultraviolet light sourcesprovided in an area that faces a placement surface of the stage on whichthe substrate is placed, and configured to irradiate the processing gasinside the processing container with ultraviolet rays, whereinirradiation intensities of the ultraviolet rays irradiated from the atleast three ultraviolet light sources are the same, wherein the at leastthree ultraviolet light sources are provided to be offset from therotation axis of the stage in a plan view, and are arranged in a lightsource arrangement direction that is a predetermined direction parallelto the placement surface of the stage in a plan view with distances fromthe at least three ultraviolet light sources to the rotation axis of thestage being different from one another, wherein the at least threeultraviolet light sources include a first ultraviolet light sourcedisposed closest to the rotation axis of the stage in a plan view, asecond ultraviolet light source disposed at an outermost position in aplan view and arranged near a peripheral edge of the stage, and a thirdultraviolet light source other than the first and second ultravioletlight sources, and wherein the third ultraviolet light source isarranged such that distances L1, L2, and L3 from the first ultravioletlight source, the second ultraviolet light source, and the thirdultraviolet light source, respectively, to the rotation axis of thestage in a plan view satisfies a relationship of L1<L3<L2.

According to (1) above, it is possible to increase a formation rate ofan oxide film while ensuring in-plane uniformity of film quality.

(2) In the substrate processing apparatus of (1) above, the distancesfrom the at least three ultraviolet light sources to the placementsurface of the stage are equal to one another.

(3) In the substrate processing apparatus of (1) or (2) above, the atleast three ultraviolet light sources are arranged at regular intervalsin the light source arrangement direction.

(4) In the substrate processing apparatus of any one of (1) to (3)above, each of the first ultraviolet light source, the secondultraviolet light source, and the third ultraviolet light source is asingle light source.

(5) In the substrate processing apparatus of (4) above, when an originin the light source arrangement direction is the rotation axis of thestage, the first ultraviolet light source and the second ultravioletlight source are located on a positive side with respect to the originin the light source arrangement direction, and the third ultravioletlight source is located on a negative side with respect to the origin inthe light source arrangement direction.

According to (5) above, it is possible to arrange the first to thirdultraviolet light sources such that a positional relationship of L1 toL3 becomes L1<L3<L2 even when each of the first to third ultravioletlight sources is wide in width.

(6) In the substrate processing apparatus of (4) or (5) above, the firstultraviolet light source, the second ultraviolet light source, and thethird ultraviolet light source are arranged so as to satisfy arelationship of L3+L1=L2−L1.

(7) In the substrate processing apparatus of (6) above, the substratehas a diameter of 300 mm, and the distance L1, the distance L2, and thedistance L3 are 35 mm, 175 mm, and 105 mm, respectively.

(8) In the substrate processing apparatus of any one of (1) to (7)above, the at least three ultraviolet light sources are provided outsidethe processing container, and the processing container includes opticalwindows configured to transmit the ultraviolet rays irradiated from theat least three ultraviolet light sources.

(9) In the substrate processing apparatus of (8) above further includesa gas cooling mechanism configured to cool down at least one of the atleast three ultraviolet light sources and the optical windows using acooling gas.

According to (9) above, it is possible to prevent a reduction intransmittance of the optical window and prolong the lifespan of theultraviolet light source.

(10) In the substrate processing apparatus of (9) above, ozone generatedoutside the processing container by the ultraviolet rays irradiated fromthe at least three ultraviolet light sources is discharged by thecooling gas.

(11) In the substrate processing apparatus of any one of (8) to (10)above further includes: a liquid cooling mechanism configured to cooldown the optical windows provided respectively to the at least threeultraviolet light sources using a cooling liquid, and the liquid coolingmechanism cools down all the optical windows provided respectively tothe at least three ultraviolet light sources using a single flow paththrough which the cooling liquid flows.

According to (11) above, it is possible to prevent a reduction intransmittance of all of the optical windows by using a structure that iseasy to attach and detach a cooling supply pipe.

(12) In the substrate processing apparatus of any one of (1) to (11)above further includes a radical supply mechanism configured to supplyradicals to a predetermined oxide film which is formed by radicalsgenerated when the processing gas supplied into the processing containerabsorbs the ultraviolet rays irradiated from the ultraviolet lightsource.

(13) There is provided a method of processing a substrate using asubstrate processing apparatus. The substrate processing apparatusincludes: a processing container in which the substrate is accommodated;a stage provided inside the processing container, and configured toplace the substrate thereon and rotate about a rotation axis thereof;and at least three ultraviolet light sources provided in an area thatfaces a placement surface of the stage on which the substrate is placed,and configured to irradiate the processing gas inside the processingcontainer with ultraviolet rays, wherein irradiation intensities of theultraviolet rays irradiated from the at least three ultraviolet lightsources are the same, wherein the at least three ultraviolet lightsources are provided to be offset from the rotation axis of the stage ina plan view, and are arranged in a light source arrangement directionthat is a predetermined direction parallel to the placement surface ofthe stage in a plan view with distances from the at least threeultraviolet light sources to the rotation axis of the stage aredifferent from one another, wherein the at least three ultraviolet lightsources include a first ultraviolet light source disposed closest to therotation axis of the stage in a plan view, a second ultraviolet lightsource disposed at an outermost position in a plan view and arrangednear a peripheral edge of the stage, and a third ultraviolet lightsource other than the first and second ultraviolet light sources, andwherein the third ultraviolet light source is arranged such thatdistances L1. L2 and L3 from the first ultraviolet light source, thesecond ultraviolet light source and the third ultraviolet light source,respectively, to the rotation axis of the stage in a plan view satisfiesa relationship of L1<L3<L2. The method includes supplying a processinggas into the processing container and irradiating, by the at least threeultraviolet light sources, the processing gas with the ultraviolet rays.The irradiation intensities of the ultraviolet rays irradiated from theat least three ultraviolet light sources are equal to one another.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the embodiments described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the embodiments describedherein may be made without departing from the spirit of the disclosures.The accompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thedisclosures.

What is claimed is:
 1. A substrate processing apparatus for processing asubstrate, comprising: a processing container in which the substrate isaccommodated; a stage provided inside the processing container, andconfigured to place the substrate thereon and rotate about a rotationaxis thereof; a gas supply mechanism configured to supply a processinggas into the processing container; and at least three ultraviolet lightsources provided in an area that faces a placement surface of the stageon which the substrate is placed, and configured to irradiate theprocessing gas inside the processing container with ultraviolet rays,wherein irradiation intensities of the ultraviolet rays irradiated fromthe at least three ultraviolet light sources are the same, wherein theat least three ultraviolet light sources are provided to be offset fromthe rotation axis of the stage in a plan view, and are arranged in alight source arrangement direction that is a predetermined directionparallel to the placement surface of the stage in a plan view withdistances from the at least three ultraviolet light sources to therotation axis of the stage being different from one another, wherein theat least three ultraviolet light sources include a first ultravioletlight source disposed closest to the rotation axis of the stage in aplan view, a second ultraviolet light source disposed at an outermostposition in a plan view and arranged near a peripheral edge of thestage, and a third ultraviolet light source other than the first andsecond ultraviolet light sources, and wherein the third ultravioletlight source is arranged such that distances L1, L2, and L3 from thefirst ultraviolet light source, the second ultraviolet light source, andthe third ultraviolet light source, respectively, to the rotation axisof the stage in a plan view satisfies a relationship of L1<L3<L2.
 2. Thesubstrate processing apparatus of claim 1, wherein the distances fromthe at least three ultraviolet light sources to the placement surface ofthe stage are equal to one another.
 3. The substrate processingapparatus of claim 2, wherein the at least three ultraviolet lightsources are arranged at regular intervals in the light sourcearrangement direction.
 4. The substrate processing apparatus of claim 3,wherein each of the first ultraviolet light source, the secondultraviolet light source, and the third ultraviolet light source is asingle light source.
 5. The substrate processing apparatus of claim 4,wherein, when an origin in the light source arrangement direction is therotation axis of the stage, the first ultraviolet light source and thesecond ultraviolet light source are located on a positive side withrespect to the origin in the light source arrangement direction, and thethird ultraviolet light source is located on a negative side withrespect to the origin in the light source arrangement direction.
 6. Thesubstrate processing apparatus of claim 5, wherein the first ultravioletlight source, the second ultraviolet light source, and the thirdultraviolet light source are arranged so as to satisfy a relationship ofL3+L1=L2−L1.
 7. The substrate processing apparatus of claim 6, whereinthe substrate has a diameter of 300 mm, and the distance L1, thedistance L2, and the distance L3 are 35 mm, 175 mm, and 105 mm,respectively.
 8. The substrate processing apparatus of claim 7, whereinthe at least three ultraviolet light sources are provided outside theprocessing container, and wherein the processing container includesoptical windows configured to transmit the ultraviolet rays irradiatedfrom the at least three ultraviolet light sources.
 9. The substrateprocessing apparatus of claim 8, further comprising: a gas coolingmechanism configured to cool down at least one of the at least threeultraviolet light sources and the optical windows using a cooling gas.10. The substrate processing apparatus of claim 9, wherein ozonegenerated outside the processing container by the ultraviolet raysirradiated from the at least three ultraviolet light sources isdischarged by the cooling gas.
 11. The substrate processing apparatus ofclaim 10, further comprising: a liquid cooling mechanism configured tocool down the optical windows provided respectively to the at leastthree ultraviolet light sources using a cooling liquid, wherein theliquid cooling mechanism cools down all the optical windows providedrespectively to the at least three ultraviolet light sources using asingle flow path through which the cooling liquid flows.
 12. Thesubstrate processing apparatus of claim 11, further comprising: aradical supply mechanism configured to supply radicals to apredetermined oxide film which is formed by radicals generated when theprocessing gas supplied into the processing container absorbs theultraviolet rays irradiated from the ultraviolet light source.
 13. Thesubstrate processing apparatus of claim 1, wherein the at least threeultraviolet light sources are arranged at regular intervals in the lightsource arrangement direction.
 14. The substrate processing apparatus ofclaim 1, wherein each of the first ultraviolet light source, the secondultraviolet light source, and the third ultraviolet light source is asingle light source.
 15. The substrate processing apparatus of claim 14,wherein the first ultraviolet light source, the second ultraviolet lightsource, and the third ultraviolet light source are arranged so as tosatisfy a relationship of L3+L1=L2−L1.
 16. The substrate processingapparatus of claim 1, wherein the at least three ultraviolet lightsources are provided outside the processing container, and wherein theprocessing container includes optical windows configured to transmit theultraviolet rays irradiated from the at least three ultraviolet lightsources.
 17. The substrate processing apparatus of claim 16, furthercomprising: a liquid cooling mechanism configured to cool down theoptical windows provided respectively to the at least three ultravioletlight sources using a cooling liquid, wherein the liquid coolingmechanism cools down all the optical windows provided respectively tothe at least three ultraviolet light sources using a single flow paththrough which the cooling liquid flows.
 18. The substrate processingapparatus of claim 1, further comprising: a radical supply mechanismconfigured to supply radicals to a predetermined oxide film which isformed by radicals generated when the processing gas supplied into theprocessing container absorbs the ultraviolet rays irradiated from theultraviolet light source.
 19. A method of processing a substrate using asubstrate processing apparatus, wherein the substrate processingapparatus includes: a processing container in which the substrate isaccommodated; a stage provided inside the processing container, andconfigured to place the substrate thereon and rotate about a rotationaxis thereof; and at least three ultraviolet light sources provided inan area that faces a placement surface of the stage on which thesubstrate is placed, and configured to irradiate the processing gasinside the processing container with ultraviolet rays, whereinirradiation intensities of the ultraviolet rays irradiated from the atleast three ultraviolet light sources are the same, wherein the at leastthree ultraviolet light sources are provided to be offset from therotation axis of the stage in a plan view, and are arranged in a lightsource arrangement direction that is a predetermined direction parallelto the placement surface of the stage in a plan view with distances fromthe at least three ultraviolet light sources to the rotation axis of thestage are different from one another, wherein the at least threeultraviolet light sources include a first ultraviolet light sourcedisposed closest to the rotation axis of the stage in a plan view, asecond ultraviolet light source disposed at an outermost position in aplan view and arranged near a peripheral edge of the stage, and a thirdultraviolet light source other than the first and second ultravioletlight sources, and wherein the third ultraviolet light source isarranged such that distances L1, L2 and L3 from the first ultravioletlight source, the second ultraviolet light source and the thirdultraviolet light source, respectively, to the rotation axis of thestage in a plan view satisfies a relationship of L<L3<L2, the methodcomprising: supplying a processing gas into the processing container andirradiating, by the at least three ultraviolet light sources, theprocessing gas with the ultraviolet rays, wherein irradiationintensities of the ultraviolet rays irradiated from the at least threeultraviolet light sources are equal to one another.